Candle



CANDLE Donald C. Walker, Lansing, 111., assignor to Standard OilCompany, Chicago, 111., a corporation of Indiana No Drawing. ApplicationJanuary 28, 1957 Serial No. 636,503

Claims. or. 67-42 to be able to control the rate at which the candleburns.

Some degree of control over the burning rate of a candle can be achievedby varying the thickness of the wick, as by increasingthe wick size tomake the candle burn at a faster rate and decreasing it to reduce theburning rate. As a method of decreasing the burning rate, however,decreasing the size of the wick sufiers from several disadvantages. wickcannot be decreasedbeyond a certain point, since it then becomes toofragile for easy handling during the manufacturing operation. Moreover,a candle having an extremely fine wick is prone to erratic burning.Minute impurities in the wax comprising the body of the candle can blockthe rise of molten wax in the wick and thus cause the flame to burn inan erratic manner or even to die out of its own accord.

It is an object of this invention to provide a candle having a reducedburning rate which is achieved without decreasing the size of the wick.Another object is to produce a candle whose burning rate can becontrolled by From a physical standpoint the size of th the addition ofcontrolled amounts of polybutenes tothe wax comprising the body of thecandle. A further object is to provide a method for the manufacture ofcandles having reduced rates of burning. Other objects will "be apparentto those skilled in the art from the following description of myinvention.

I have discovered that the burning rate of a wax candle can be reducedto a controlled extent by the addition of up to about 10% by weight,preferably from about 1% to about 5 of a polybutene having a molecularweight within the range from about 50,000 to about 500,000, preferablyirom about 100,000 to about 300,000, to the wax comprising the body ofthe candle. The extent of reduction in the burning rate is dependent onboth the amount of pol-ybutene added and its molecular weight, i. e.,other things (wick size, type and melting point of the wax, diameter ofthe candle, etc.) being equal, the burning rate of the candle isdecreased by increasing the amount of polybutene of a given molecularweight or by increasing the molecular weight while keeping the quantityadded constant. By means of my invention it is possible to de crease theburning rate without the necessity for decreasin the diameter of thewick. In this manner the difliculculties normally attending the use ofan extra-fine wick are obviated.

The polybutenes which are contemplated for use in my invention includepolymers of l-butene, Z-butene, and isobutylene. Methods for theproduction of these polybutones are Well known in the art. In general,these methods involve condensing the olefin feed at a low temperaturewith a Friedel-Crafts type of catalyst such as boron fluoride oraluminum chloride.

The polybutenes suitable for use in accordance with my invention have amolecular weight within the range from 2521,33 Patented Apr. 22, 1958 2about 50,000 to about 500,000. I have found that if the molecular weightis less than about 50,000 the addition of polybutenes has relativelylittle effect on the burning rate .of the candle. If on the other handthe molecular weight exceeds about 500,000 it becomes diflicult todissolve the polybutene in the wax. For these reasons I prefer to usepolymers having molecular weights within the range from about 100,000 toabout 300,000, since these are readily incorporated in the wax whichforms the body of the candle and at the same time relatively smallamounts thereof have an appreciable effect on the burning rate of thecandle, e. g., a reduction in burning rate of about 5% or more when usedin amounts of about 0.5% by weight. The polymer is added to the wax inan amount ranging from about 0.1% to about 10% by weight, and preferablyWithin the range from about 1% to about 5%, the amount to be used in agiven case depending on the degree of reduction in burning rate which isdesired and on the molecular weight of the polybutene within the definedrange. I have found that the addition of a polybutene of the definedclass in an amount ranging from about 12% to about depending on themolecular weight, causes the burning rate to decrease to such an extentthat the candle burns only with great difficulty, or not at all.

My invention is applicable to candles having a body made of any of thenormally solid waxy materials commonly used for candle manufacture,including petroleum wax, ceresin wax, montan wax, beeswax andspermaceti. When petroleum waxes are used it is customary to employ aparaffin wax fraction having a melting point between about 115 and 170F., preferablybetween about 125 and 140 F., although other types ofpetroleum wax such as motor oil wax and microcrystalline wax can alsobepresent in admixture with the paraffin wax.

The wax used in molded, hand-dipped, and decorative candles usuallycontains stearic acid in an amount from about 1% to 50% by weight andpreferably from about 10% to 40%. The stearic acid, which can besingle-, double-, or triple-pressed, 'is added for the purpose ofhardening the candle composition, raising the bending (or softening)point, and lowering the melting point. My invention is equallyapplicable to candles made of'wax containing stearic acid and to thosewherein no stearic acid is used.

The polybutenes can be incorporated in the Wax by heating the latter toa temperature in the vicinity of 400 R, adding the polybutene andstirring until a homogeneous mixture is obtained. A preferred method,however, comprises making a solution of the polymer in a hydrocarbonsolvent such as hexane, toluene, or naphtha, dissolving the wax'in thissolution, and stripping off the solvent by heating the mixture to atemperature of about 250 F. Alternatively, the solvent can be strippedoff at a lower temperature by vacuum distillation. This latter methodavoids the use of high temperature and the presence of objectionableoxidation products which may be formed in the wax thereby.

My invention is particularly useful for prolonging the burning ofcandles used in spring-loaded holders. These holders, usually of smallsize, completely encase the candle and contain an internal spring whichforces the candle upward against a stop at the top of the holder, sothat the position of the flame remains fixed. Such holders are commonlyprovided with a shade and are used for decorative purposes rather thanfor illumination. A

candle of relatively small size, yet capable of burning for an extendedperiod of time, can be used to great advantage in a holder of this type.

As has been pointed out above, the addition of polybutene polymers inamounts exceeding about 10% by weight reduces the burning rate to suchan extent that the candle burns with difliculty, if at all. This efiectcan be advantageously used to make a candle which is self-snufling, i.e.,. one which will extinguish-itself when the flame reaches apredetermined position along the length of the candle, by forming thecandle in two sections with the lower section containing a gross amountof polybutene polymers, i. e., between about 12% and 50%, depending onthe molecular weight of the polybutene. For example, a candle with alower section comprising about of a polybutene having a molec ularweight of about 300,000 automatically extinguishes itself when the flamereaches the section of the body which contains the high proportion ofpolybutene, and can be used to advantage in applications where thecandle is left unattended for long periods of time and where for reasonsof safety or otherwise, it is desired that it stop burning before beingentirely consumed.

The efiect of the addition of polybutenes on the burning rate of waxcandles is illustrated by the following experimental data. The tablebelow shows the burning rates of five candles, the. wax bodies of whichcontained varying amounts ofisobutylene polymer having a molecularweight of about 300,000. The candles were of identical size, about 4 /2inches long and 964 inch in diameter, and contained 15-strand braidedwicks. The wax used was a refined petroleum paraflin wax having amelting point of 135-137 F. In each case the candle contained 3% byweight of double-pressed stearic acid. The burning rate was obtained byWeighing the candle and then burning it in a draft-free space until onlya stub of about one inch in length was left, at which time the stub andthe accumulated drippings (if any) were weighed. The burning rate wascalculated by dividing the total loss in weight by the time during whichthe candle was burning. The percentage figures in the following tableand in the appended claims are percentages by weight, based on the finalcomposition, unless otherwise indicated.

The data of the table show that the burning rate was reduced to about /3of its original value by the addition of 4% of polyisobutylene having amolecular weight of about 300,000. The burning rate can be decreased ina similar manner by using smaller quantities of a polybutene having amolecular weight greater than 300,000 (i. e., between 300,000 and500,000) or larger quantities of a polybutene having a molecular weightless than 300,000, i. e., within the range of 50,000 to 300,000. Forexample, burning rates equivalent to those given in the table can beachieved by using a polymer having a molecular weight of about 100,000in amounts about 1.5 to 2.5 times those given in the table. Although atthese decreased burning rates the size of the flame naturally decreases,nevertheless the candle burns smoothly, without any evidence of atendency to self-extinguishment such as might be expected if smallerwicks are used.

While I have described my invention with reference to specificembodiments thereof, the same are given by way of illustration only.Modifications and variations will be apparent from my description tothose skilled in the art.

Having described my invention, I claim:

1. A candle having a reduced burning rate which comprises essentially awick and a normally solid wax body, said wax body comprising from about0.1% to about 10% of a polybutene having a molecular weight from about50,000 to about 500,000.

2. The candle of claim 1 wherein said normally solid wax is petroleumwax having a melting point within the range of about to about F., andwherein said polybutene is present in an amount between about 1% andabout 5%.

3. A candle having a reduced burning rate which comprises essentially awickand a normally solid wax body, said body comprising petroleum wax,from about 0.1% to about 10% of an isobutylene polymer having amolecular weight within the range of about 100,000 to about 300,000 andfrom about 1% to about 50% of stearic acid.

4. The candle of claim 3 wherein said body comprises between about 1%and about 5% of said isobutylene polymer and wherein said petroleum Waxis a paraflin wax having a melting point between about 115 and about 170F.

, 5. A self-snulfing candle which comprises essentially a wick and awax'body, said body being divided along its length into two unequalsections, a major upper section comprising from about 0.1% to about 10%of a polybutene having a molecular weight from about 50,000 to about500,000 and a lower minor section comprising said polybutene in anamount from about 12% to about 50% and suflicient, when the candle isburned, to cause the flame to be extinguished when it reaches said minorsection.

References Cited in the file of this patent Warth: The Chemistry andTechnology of Waxes, Reinhold Publishing Corporation, New York, NewYork, copyright 1956, pages 504-506 and 511 only are needed.

1. A CANDLE HAVING A REDUCED BURNING RATE WHICH COMPRISES ESSENTIALLY AWICK AND A NORMALLY SOLID WAX BODY, SAID WAX BODY COMPRISING FROM ABOUT0.1% TO ABOUT 10% OF A POLYBUTENE HAVING A MOLECULAR WEIGHT FROM ABOUT50,000 TO ABOUT 500,000.